Permo-Mesozoic Canavese sediments are pinched in between the pre-Alpine
high-grade metamorphic Ivrea Zone and the Alpine metamorphosed Sesia
Zone along the Insubric Line W of Locarno. According to the ``illite
crystallinity'' these sediments were deformed under anchi- and
epizonal conditions. Synkinematically formed white mica in the
mylonitized Canavese sediments yields the following K-Ar age ranges:
60-76 Ma at the southwestern end, 28-43 Ma in the central part and 19-26
Ma in the northeastern part of the Insubric Line W of Locarno. The
youngest age group dates the main uplift and dextral strike-slip
movements of the Insubric Line, comprising mylonites in the NE and
cataclasites in the SW. This activity correlates with Late Oligocene to
Early Miocene rapid cooling and uplift of the Central Alps